In the retail industry, bi-optical scanners, each having both a horizontal window and an upright window, have been used to electro-optically read targets, such as one-dimensional bar code symbols, particularly of the Universal Product Code (UPC) type, and two-dimensional bar code symbols, such as PDF417 and QR codes, at full-service, point-of-transaction checkout systems operated by checkout clerks in supermarkets, warehouse clubs, department stores, and other kinds of retailers, for many years. Products to be purchased bear identifying target symbols and are typically slid by a clerk across a respective window, e.g., from right to left, or from left to right, in a “swipe” mode, to a bagging area. Alternatively, the clerk merely presents the target symbol on the product to, and holds the product momentarily steady at, a central region of a respective window in a “presentation” mode, prior to placing the product in the bagging area. The choice depends on the type of target, on clerk preference, and on the layout of the system.
Some checkout systems are laser-based workstations, and project a multitude of laser scan lines through a respective window. When at least one of the scan lines sweeps over a target symbol associated with a product, the symbol is processed, decoded and read. The multitude of scan lines is typically generated by a scan pattern generator which includes a laser for emitting a laser beam at a mirrored component mounted on a shaft for rotation by a motor about an axis. A plurality of stationary mirrors is arranged about the axis. As the mirrored component turns, the laser beam is successively reflected onto the stationary mirrors for reflection therefrom through the respective window as a scan pattern of the laser scan lines.
Other checkout systems are imager-based workstations, and have one or more solid-state imagers, or image sensors, analogous to those conventionally used in consumer digital cameras. Each imager has a one- or two-dimensional array of photocells or light sensors (also known as pixels), and an imaging lens assembly for capturing return light scattered and/or reflected from a target being imaged through a respective window over a field of view, and for projecting the return light onto the sensor array to initiate capture of an image of the target over a range of working distances in which the target can be read. The target may be a symbol, as described above, either printed on a label or displayed on a display screen of an electronic device, such as a smart phone. The target may also be a form, such as a document, label, receipt, signature, driver's license, employee badge, or payment/loyalty card, etc., each bearing alphanumeric characters, as well as a picture, to be imaged. Such an imager may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device and associated circuits for producing and processing electrical signals corresponding to a one- or two-dimensional array of pixel data over the field of view. These electrical signals are decoded and/or processed by a programmed microprocessor or controller into data related to the target being electro-optically read, e.g., decoded data indicative of a symbol, or into a picture of a target other than a symbol.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein